yaffs_guts.c

YAFFS

	int chunksBefore = yaffs_GetErasedChunks(dev);
	int chunksAfter;

	yaffs_ExtendedTags tags;

	yaffs_BlockInfo *bi = yaffs_GetBlockInfo(dev, block);

	yaffs_Object *object;

	bi->blockState = YAFFS_BLOCK_STATE_COLLECTING;

	T(YAFFS_TRACE_TRACING,
	  (TSTR("Collecting block %d, in use %d, shrink %d, " TENDSTR), block,
	   bi->pagesInUse, bi->hasShrinkHeader));

	/*yaffs_VerifyFreeChunks(dev); */

	bi->hasShrinkHeader = 0;	/* clear the flag so that the block can erase */

	/* Take off the number of soft deleted entries because
	 * they're going to get really deleted during GC.
	 */
	dev->nFreeChunks -= bi->softDeletions;

	dev->isDoingGC = 1;

	if (!yaffs_StillSomeChunkBits(dev, block)) {
		T(YAFFS_TRACE_TRACING,
		  (TSTR
		   ("Collecting block %d that has no chunks in use" TENDSTR),
		   block));
		yaffs_BlockBecameDirty(dev, block);
	} else {

		__u8 *buffer = yaffs_GetTempBuffer(dev, __LINE__);

		for (chunkInBlock = 0, oldChunk = block * dev->nChunksPerBlock;
		     chunkInBlock < dev->nChunksPerBlock
		     && yaffs_StillSomeChunkBits(dev, block);
		     chunkInBlock++, oldChunk++) {
			if (yaffs_CheckChunkBit(dev, block, chunkInBlock)) {

				/* This page is in use and might need to be copied off */

				markNAND = 1;

				yaffs_InitialiseTags(&tags);

				yaffs_ReadChunkWithTagsFromNAND(dev, oldChunk,
								buffer, &tags);

				object =
				    yaffs_FindObjectByNumber(dev,
							     tags.objectId);

				T(YAFFS_TRACE_GC_DETAIL,
				  (TSTR
				   ("Collecting page %d, %d %d %d " TENDSTR),
				   chunkInBlock, tags.objectId, tags.chunkId,
				   tags.byteCount));

				if (!object) {
					T(YAFFS_TRACE_ERROR,
					  (TSTR
					   ("page %d in gc has no object "
					    TENDSTR), oldChunk));
				}

				if (object && object->deleted
				    && tags.chunkId != 0) {
					/* Data chunk in a deleted file, throw it away
					 * It's a soft deleted data chunk,
					 * No need to copy this, just forget about it and 
					 * fix up the object.
					 */

					object->nDataChunks--;

					if (object->nDataChunks <= 0) {
						/* remeber to clean up the object */
						dev->gcCleanupList[cleanups] =
						    tags.objectId;
						cleanups++;
					}
					markNAND = 0;
				} else if (0
					   /* Todo object && object->deleted && object->nDataChunks == 0 */
					   ) {
					/* Deleted object header with no data chunks.
					 * Can be discarded and the file deleted.
					 */
					object->chunkId = 0;
					yaffs_FreeTnode(object->myDev,
							object->variant.
							fileVariant.top);
					object->variant.fileVariant.top = NULL;
					yaffs_DoGenericObjectDeletion(object);

				} else if (object) {
					/* It's either a data chunk in a live file or
					 * an ObjectHeader, so we're interested in it.
					 * NB Need to keep the ObjectHeaders of deleted files
					 * until the whole file has been deleted off
					 */
					tags.serialNumber++;

					dev->nGCCopies++;

					if (tags.chunkId == 0) {
						/* It is an object Id,
						 * We need to nuke the shrinkheader flags first
						 * We no longer want the shrinkHeader flag since its work is done
						 * and if it is left in place it will mess up scanning.
						 * Also, clear out any shadowing stuff
						 */

						yaffs_ObjectHeader *oh;
						oh = (yaffs_ObjectHeader *)buffer;
						oh->isShrink = 0;
						oh->shadowsObject = -1;
						tags.extraShadows = 0;
						tags.extraIsShrinkHeader = 0;
					}

					newChunk =
					    yaffs_WriteNewChunkWithTagsToNAND(dev, buffer, &tags, 1);

					if (newChunk < 0) {
						retVal = YAFFS_FAIL;
					} else {

						/* Ok, now fix up the Tnodes etc. */

						if (tags.chunkId == 0) {
							/* It's a header */
							object->chunkId =  newChunk;
							object->serial =   tags.serialNumber;
						} else {
							/* It's a data chunk */
							yaffs_PutChunkIntoFile
							    (object,
							     tags.chunkId,
							     newChunk, 0);
						}
					}
				}

				yaffs_DeleteChunk(dev, oldChunk, markNAND, __LINE__);

			}
		}

		yaffs_ReleaseTempBuffer(dev, buffer, __LINE__);


		/* Do any required cleanups */
		for (i = 0; i < cleanups; i++) {
			/* Time to delete the file too */
			object =
			    yaffs_FindObjectByNumber(dev,
						     dev->gcCleanupList[i]);
			if (object) {
				yaffs_FreeTnode(dev,
						object->variant.fileVariant.
						top);
				object->variant.fileVariant.top = NULL;
				T(YAFFS_TRACE_GC,
				  (TSTR
				   ("yaffs: About to finally delete object %d"
				    TENDSTR), object->objectId));
				yaffs_DoGenericObjectDeletion(object);
			}

		}

	}

	if (chunksBefore >= (chunksAfter = yaffs_GetErasedChunks(dev))) {
		T(YAFFS_TRACE_GC,
		  (TSTR
		   ("gc did not increase free chunks before %d after %d"
		    TENDSTR), chunksBefore, chunksAfter));
	}

	dev->isDoingGC = 0;

	return YAFFS_OK;
}

/* New garbage collector
 * If we're very low on erased blocks then we do aggressive garbage collection
 * otherwise we do "leasurely" garbage collection.
 * Aggressive gc looks further (whole array) and will accept less dirty blocks.
 * Passive gc only inspects smaller areas and will only accept more dirty blocks.
 *
 * The idea is to help clear out space in a more spread-out manner.
 * Dunno if it really does anything useful.
 */
static int yaffs_CheckGarbageCollection(yaffs_Device * dev)
{
	int block;
	int aggressive;
	int gcOk = YAFFS_OK;
	int maxTries = 0;

	if (dev->isDoingGC) {
		/* Bail out so we don't get recursive gc */
		return YAFFS_OK;
	}
	
	/* This loop should pass the first time.
	 * We'll only see looping here if the erase of the collected block fails.
	 */

	do {
		maxTries++;
		if (dev->nErasedBlocks < dev->nReservedBlocks) {
			/* We need a block soon...*/
			aggressive = 1;
		} else {
			/* We're in no hurry */
			aggressive = 0;
		}

		block = yaffs_FindBlockForGarbageCollection(dev, aggressive);

		if (block > 0) {
			dev->garbageCollections++;
			if (!aggressive) {
				dev->passiveGarbageCollections++;
			}

			T(YAFFS_TRACE_GC,
			  (TSTR
			   ("yaffs: GC erasedBlocks %d aggressive %d" TENDSTR),
			   dev->nErasedBlocks, aggressive));

			gcOk = yaffs_GarbageCollectBlock(dev, block);
		}

		if (dev->nErasedBlocks < (dev->nReservedBlocks) && block > 0) {
			T(YAFFS_TRACE_GC,
			  (TSTR
			   ("yaffs: GC !!!no reclaim!!! erasedBlocks %d after try %d block %d"
			    TENDSTR), dev->nErasedBlocks, maxTries, block));
		}
	} while ((dev->nErasedBlocks < dev->nReservedBlocks) && (block > 0)
		 && (maxTries < 2));

	return aggressive ? gcOk : YAFFS_OK;
}

/*-------------------------  TAGS --------------------------------*/

static int yaffs_TagsMatch(const yaffs_ExtendedTags * tags, int objectId,
			   int chunkInObject)
{
	return (tags->chunkId == chunkInObject &&
		tags->objectId == objectId && !tags->chunkDeleted) ? 1 : 0;

}


/*-------------------- Data file manipulation -----------------*/

static int yaffs_FindChunkInFile(yaffs_Object * in, int chunkInInode,
				 yaffs_ExtendedTags * tags)
{
	/*Get the Tnode, then get the level 0 offset chunk offset */
	yaffs_Tnode *tn;
	int theChunk = -1;
	yaffs_ExtendedTags localTags;
	int retVal = -1;

	yaffs_Device *dev = in->myDev;

	if (!tags) {
		/* Passed a NULL, so use our own tags space */
		tags = &localTags;
	}

	tn = yaffs_FindLevel0Tnode(dev, &in->variant.fileVariant, chunkInInode);

	if (tn) {
		theChunk = yaffs_GetChunkGroupBase(dev,tn,chunkInInode);

		retVal =
		    yaffs_FindChunkInGroup(dev, theChunk, tags, in->objectId,
					   chunkInInode);
	}
	return retVal;
}

static int yaffs_FindAndDeleteChunkInFile(yaffs_Object * in, int chunkInInode,
					  yaffs_ExtendedTags * tags)
{
	/* Get the Tnode, then get the level 0 offset chunk offset */
	yaffs_Tnode *tn;
	int theChunk = -1;
	yaffs_ExtendedTags localTags;

	yaffs_Device *dev = in->myDev;
	int retVal = -1;

	if (!tags) {
		/* Passed a NULL, so use our own tags space */
		tags = &localTags;
	}

	tn = yaffs_FindLevel0Tnode(dev, &in->variant.fileVariant, chunkInInode);

	if (tn) {

		theChunk = yaffs_GetChunkGroupBase(dev,tn,chunkInInode);

		retVal =
		    yaffs_FindChunkInGroup(dev, theChunk, tags, in->objectId,
					   chunkInInode);

		/* Delete the entry in the filestructure (if found) */
		if (retVal != -1) {
			yaffs_PutLevel0Tnode(dev,tn,chunkInInode,0);
		}
	} else {
		/*T(("No level 0 found for %d\n", chunkInInode)); */
	}

	if (retVal == -1) {
		/* T(("Could not find %d to delete\n",chunkInInode)); */
	}
	return retVal;
}

#ifdef YAFFS_PARANOID

static int yaffs_CheckFileSanity(yaffs_Object * in)
{
	int chunk;
	int nChunks;
	int fSize;
	int failed = 0;
	int objId;
	yaffs_Tnode *tn;
	yaffs_Tags localTags;
	yaffs_Tags *tags = &localTags;
	int theChunk;
	int chunkDeleted;

	if (in->variantType != YAFFS_OBJECT_TYPE_FILE) {
		/* T(("Object not a file\n")); */
		return YAFFS_FAIL;
	}

	objId = in->objectId;
	fSize = in->variant.fileVariant.fileSize;
	nChunks =
	    (fSize + in->myDev->nBytesPerChunk - 1) / in->myDev->nBytesPerChunk;

	for (chunk = 1; chunk <= nChunks; chunk++) {
		tn = yaffs_FindLevel0Tnode(in->myDev, &in->variant.fileVariant,
					   chunk);

		if (tn) {

			theChunk = yaffs_GetChunkGroupBase(dev,tn,chunk);

			if (yaffs_CheckChunkBits
			    (dev, theChunk / dev->nChunksPerBlock,
			     theChunk % dev->nChunksPerBlock)) {

				yaffs_ReadChunkTagsFromNAND(in->myDev, theChunk,
							    tags,
							    &chunkDeleted);
				if (yaffs_TagsMatch
				    (tags, in->objectId, chunk, chunkDeleted)) {
					/* found it; */

				}
			} else {

				failed = 1;
			}

		} else {
			/* T(("No level 0 found for %d\n", chunk)); */
		}
	}

	return failed ? YAFFS_FAIL : YAFFS_OK;
}

#endif

static int yaffs_PutChunkIntoFile(yaffs_Object * in, int chunkInInode,
				  int chunkInNAND, int inScan)
{
	/* NB inScan is zero unless scanning. 
	 * For forward scanning, inScan is > 0; 
	 * for backward scanning inScan is < 0
	 */
	 
	yaffs_Tnode *tn;
	yaffs_Device *dev = in->myDev;
	int existingChunk;
	yaffs_ExtendedTags existingTags;
	yaffs_ExtendedTags newTags;
	unsigned existingSerial, newSerial;

	if (in->variantType != YAFFS_OBJECT_TYPE_FILE) {
		/* Just ignore an attempt at putting a chunk into a non-file during scanning
		 * If it is not during Scanning then something went wrong!
		 */
		if (!inScan) {
			T(YAFFS_TRACE_ERROR,
			  (TSTR
			   ("yaffs tragedy:attempt to put data chunk into a non-file"
			    TENDSTR)));
			YBUG();
		}

		yaffs_DeleteChunk(dev, chunkInNAND, 1, __LINE__);
		return YAFFS_OK;
	}

	tn = yaffs_AddOrFindLevel0Tnode(dev, &in->variant.fileVariant,
					chunkInInode);
	if (!tn) {
		return YAFFS_FAIL;
	}

	existingChunk = yaffs_GetChunkGroupBase(dev,tn,chunkInInode);

	if (inScan != 0) {
		/* If we're scanning then we need to test for duplicates
		 * NB This does not need to be efficient since it should only ever 
		 * happen when the power fails during a write, then only one
		 * chunk should ever be affected.
		 *
		 * Correction for YAFFS2: This could happen quite a lot and we need to think about efficiency! TODO
		 * Update: For backward scanning we don't need to re-read tags so this is quite cheap.
		 */

		if (existingChunk != 0) {
			/* NB Right now existing chunk will not be real chunkId if the device >= 32MB
			 *    thus we have to do a FindChunkInFile to get the real chunk id.
			 *
			 * We have a duplicate now we need to decide which one to use:
			 *
			 * Backwards scanning YAFFS2: The old one is what we use, dump the new one.
			 * Forward scanning YAFFS2: The new one is what we use, dump the old one.
			 * YAFFS1: Get both sets of tags and compare serial numbers.
			 */

			if (inScan > 0) {
				/* Only do this for forward scanning */
				yaffs_ReadChunkWithTagsFromNAND(dev,
								chunkInNAND,
								NULL, &newTags);

				/* Do a proper find */
				existingChunk =
				    yaffs_FindChunkInFile(in, chunkInInode,
							  &existingTags);
			}

			if (existingChunk <= 0) {
				/*Hoosterman - how did this happen? */

				T(YAFFS_TRACE_ERROR,
				  (TSTR
				   ("yaffs tragedy: existing chunk < 0 in scan"
				    TENDSTR)));

			}

			/* NB The deleted flags should be false, otherwise the chunks will 
			 * not be loaded during a scan
			 */

			newSerial = newTags.serialNumber;
			existingSerial = existingTags.serialNumber;

			if ((inScan > 0) &&
			    (in->myDev->isYaffs2 ||
			     existingChunk <= 0 ||
			     ((existingSerial + 1) & 3) == newSerial)) {
				/* Forward scanning.                            
				 * Use new
				 * Delete the old one and drop through to update the tnode
				 */
				yaffs_DeleteChunk(dev, existingChunk, 1,
						  __LINE__);
			} else {
				/* Backward scanning or we want to use the existing one
				 * Use existing.
				 * Delete the new one and return early so that the tnode isn't changed
				 */
				yaffs_DeleteChunk(dev, chunkInNAND, 1,
						  __LINE__);
				return YAFFS_OK;
			}
		}

	}

	if (existingChunk == 0) {
		in->nDataChunks++;
	}

	yaffs_PutLevel0Tnode(dev,tn,chunkInInode,chunkInNAND);

	return YAFFS_OK;
}

static int yaffs_ReadChunkDataFromObject(yaffs_Object * in, int chunkInInode,
					 __u8 * buffer)
{
	int chunkInNAND = yaffs_FindChunkInFile(in, chunkInInode, NULL);

	if (chunkInNAND >= 0) {
		return yaffs_ReadChunkWithTagsFromNAND(in->myDev, chunkInNAND,
						       buffer, NULL);
	} else {
		T(YAFFS_TRACE_NANDACCESS,
		  (TSTR("Chunk %d not found zero instead" TENDSTR),
		   chunkInNAND));
		/* get sane (zero) data if you read a hole */
		memset(buffer, 0, in->myDev->nBytesPerChunk);	
		return 0;
	}

}

void yaffs_DeleteChunk(yaffs_Device * dev, int chunkId, int markNAND, int lyn)
{
	int block;
	int page;
	yaffs_ExtendedTags tags;
	yaffs_BlockInfo *bi;

	if